1. Field of the Invention
The present invention pertains to a method for the continuous preparation of a sugar or sugarless confection from a sugar or sugarless bulking agent. More specifically, the present method comprises extrusion mixing a bulking agent in a twin screw extruder, configured to include a minimum time for melting the bulking agent. The twin screw extruder is equipped with multiple heating zones, forward feed screws, forward compression screws, reverse flight screws, forward mixing paddles, an orifice plug, and a pressure control valve. The twin screw extruder is also equipped with a vent port configured to include a minimum evaporation time to reduce the moisture content of the confection to less than about 2%.
2. Description of the Background
The preparation of confectionery formulations is historically well known and has changed little through the years. Confectionery items have been classified as either "hard" confectionery or "soft" confectionery. In general, a hard confectionery has a candy base composed of a mixture of sugar and other carbohydrate bulking agents kept in an amorphous or glassy condition. This candy base is considered a solid syrup of sugars generally containing up to about 92% sugar, up to about 55% corn syrup, and from about 0.1% to about 5% water, by weight. The syrup component is generally prepared from sucrose and corn syrup but may include other materials. Further ingredients such as flavoring agents, sweetening agents, acidifying agents and coloring agents may also be added. Confectionery formulations are routinely prepared by conventional methods such as those involving fire coolers, vacuum cookers, and scraped-surface cookers, also referred to as high speed atmospheric cookers.
The use of PALATINIT.RTM. (isomalt, Suddeutsche Zucker) based high-boiled sugarless product formulations has generated interest in both international and domestic markets. A problem with the preparation of such confections is that current prototype formulations require the need for higher than normal cooking temperatures (290.degree. F.-330.degree. F.) to achieve an acceptable final product moisture. These high temperature ranges push current cooking systems to their upper limits of operation (120 psi at 340.degree. F.). At this high cooking temperature, the discharge viscosity of the isomalt candy base is very low compared with conventional production formulations. This low viscosity isomalt candy base has poor water vapor removal properties during vacuum discharge and handing difficulties during the remaining stages of production. Because isomalt has a relatively low water solubility, additional water and higher temperatures are required to process the bulking agent. An extended period of mixing in the predissolver stage of the cooker operation also helps maintain isomalt in solution.
Methods for extrusion cooking of sugar confectionery are known, as in the British Food Manufacturing Industries Research Association, Research Reports No. 496, Dec., 1984. A method for continuously preparing a chewing gum in a co-rotating twin screw extruder and reducing agglomerations by employing dual gum base injection is disclosed in U.S. Pat. No. 5,135,760. A method for preparing polydextrose from a reducing polysaccharide and a polyol in a co-rotating twin screw extruder is disclosed in U.S. Pat. No. 5,051,500.